Treatment of steel rails.



Ti. A. LEWIS. W. R. SHIMER & W. J. THOMAS,

TREATMENT OF STEEL RAILS.

. 7 APPLICATION FILED MAY T5. T915. L fifffiy m a w V1. m L 0 m N P M W MM w ran snares PATENT canton.

ROY A. LEWIS, WILLIAM ROBERT SI-IIMER, AND WILLIAM J. THOMAS, OF'BETHLEHEM,

PENNSYLVANIA, ASSIGNORS TO BETHLEHEM STEEL COMPANY, OF SOUTH BETHLE- HEM, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

TREATMENT OF STEEL RAILS.

To all whom it may concern:

Be it known that we, Roy A. LIAM ROBERT SHIMER, and WILLIAM J.

THOMAS, all citizens of the United States,

and residents of Bethlehem, Northampton county, Pennsylvania, have jointly invented new and useful Improvements in the Treat ment of-Steel Rails, of which the following is a specification, reference being had to the treating of rails after the last forming oper ation and while they retain part of the heat of the final rolling or formin operation. Our invention also consists in t e modes of treatment which we shall hereinafter describe and claim.

A typical manner of carrying out our invention in connection with the apparatus shown in the drawings is as follows:

The rail is preferabl heated bloom, in order t at it may leave the rollsat a hi h finishing temperature, so that it may befree from internal strains after the rolling operation has been completed. We have found that the railris at a temperature of between 1700 and 2075" F. as it leaves the finishing rolls, and is cooled to for from five to ten minutes, in order to cool the rail rapidly and thereby prevent, as far as possible, the formation of free ferrite or laminated pearlite, and retains, as far as is possible, the structure of the metal'in the condition in which it comes from the finishing rolls. As the rail is cooled rapidly to well below the critical or calescence point (which is about 1370 F.), that is, to about 1000 to 1100 F., the separation of the constituents, free ferrite, laminated pearlite and grain growths, is prevented to a large degree and the homogeneous character of the metalis substantially maintained.

The rail, after cooling, is conveyed to a continuousre-heating furnace B in which it remains for a period of preferably between forty-five minutes to an hour. The charg- LEWIS, WIL- rolled from a re- Specification of Letters Patent. Patgnted N 26, 1918,, Application filed May 15,1915. Serial No. 28,281. I

ing'end of the furnace is about 1300 F., and as the rail is advanced the furnace temperature-increases, so as to bring the rail, dur- .1ng the latter part of its travel, to approximately between 1400 and 1500 F. This temperature is maintained so as to insure a thorough and uniform heating of the rail, so that, when the rail leaves the furnace, all of its parts will have reached approximately the same temperature, at which the iron and carbon will exist in the rail in a homogeneous solid solution.

As the rail is discharged from the furnace it is again cooled quickly, preferably in oil or any other suitable cooling medium,-at C. By cooling quickly the steel is hardened and the solid solution of iron and carbon is maintained as far as possible without change. The cooling is preferably effected in three or four. minutes, and the temperature is reduced from above the critical point to Proferably between 600 and 1000 F., depending largely on the cooling medium used. If oil is used, it is cooled to or below 600 F.

After the second cooling, and while the rail still contains an appreciable amount of heat, it is carried to an annealing furnace D, in. which the temperature of the charging end is about 1000 F. and is increased gradually toward the middle of the furnace, and from this point to the discharge end the furnace will be at a temperature necessary to heat the rail uniformly to between 1000 to 1250 F., (that is, below the recalescence point, which is about 1250 F.) depending on thecomposition of the rails and 'the required physical and wearing qualities.

ishing temperature may be utilized. Byv

using an air blast or other cooling medium by which the rail is cooled quickly, much time is saved in completing the treatment of the rail, and it must be cooled quickly in order to prevent, as far as possible, the separation of free ferrite and grain growth, which would occur if the rail were allowed to cool in the usual manner. 1

As the rail is preferably not cooled to below 1000 F., it being only necessary to cool it below the critical point, it can be reheated quickly in the re-heating furnace, which is for the purpose of raising the steel the heat of the rail in the subsequent annealing operation. The second cooling acts both to harden and refine the rail, the final hardness depending on the rate of cooling and the temperature at which the rail is heated in the annealing furnace.

in the annealing furnace the rail remains in the furnace a sufficient length of time so as to be uniformly heated throughout and is relieved of st *ains, and is heated to the desired temperature to give it the requisite strength. hardness and ductility.

li o have found that rails containing, (1) .tl'lj}, carbon. 158% manganese; .71.% carbon. ."i'iif/O manganese. and with silicon, sulfur and PhOSPhOIllS in the percentages usually found in rail steel, treated in accordance with our invention, have given the following results in comparison with untreated rails of the same coniposition:

(1.) .6155 carbon, 08;; manganese.

Treated. Untreated.

130,000 ll)S.i 107,500 lbs. 20,000 i 54,000 17 15% 43. a /C 24. 03% -is i 214 .7170 carbon, .76% manganese.

Treated.

Untreated.

138,000 lbs. 120.000 lbs.

El? c limit cc 88,000 6e,000 Elongation 19.591, 13.59,. Reduction in area 48.8% 22.3% Briuell hardness No ..j 227 the treatedsteel showing the following in creases over the untreated steel:

Specimen Specimen No. 1. No. 2.

Tensile s rength per sq. in 22,500 lbs. 18,000 lbs. llasuc limit per in .i r. 20,000 22.000 2.5 g 6 '7 I cl ion in area 19. 22 7 26. Brineil hardness No 51 quickly below i200 i Leonie-e since by employing them We are enabled to heat the rail at a uniform temperature above the critical point, so that when the rails are cooled in the loath C. all oi the parts of the rail -will be aiiected uniformly. We have found, however, that good results may be obtained by eliminating the re-heating treatment in the furnace B and one of the cooling treatments; that is We take the rail as it comes from the hot saw and cool it to about 1000 F. and pass it directly into the annealing furnace D, but the rails treated by this method are not as uniform as those treated by the method which we have described above, for the reason that. as the rail, comes from the rolling operation its flanges and webs Will have cooled to greater extent than have the head and base of the rail, and hence, in the resulting product, the steel is not nearly so uniform as when the ire-heating operation is included in carrying out our process.

The terms and expressions which We have employed are used as terms oi? description and not of limitation, and We, have no intention, in the use olisuch terms and expressions, of excluding any equivalent for the features which We have described. but recognize that various modifications are possihle within the scope of the invention claimed;

What we eann is:

of heat-treating; rails, in taking a hie-lily heated rail as it. comes from the iinal Iorniing operation, cooling it guiekl v to below 1300 above 1000 F convey ngit to a nearing rurnace and heating it therein until it reaches uniform temperature above 1400 l and below 1500 F. then cooling rapidly to between 1000 and 600 and then passing it through an annealing furnace. in which the rail is uniformly heated to between l000 and 1200 and then coolin ;-.ne method of a heat-treating rails, which consists in taking a highly heated rail as it comes from the final forming operation and While itsteniperature above 1000 and below 2075 ll. cooling it quickly in air spray to helon 1300 F. and above 1000 to prevent the separalionv of tree ferrite, then passing the rail through a heating turnaceend heating the rail in all of its parts to a temperature not less than H00 maintaining; the rail at such temperature for a deterr inate period ol time. and cooling quickly below 1000 ll. ire-heating to not. less th n 1000 but and maintaining it. at such temperature for a determinate period of time. and then cooling.

3. The method of 7 heat treating rails, which consists in taking a hi hly heated "ail coines trons the eration, and whilethe temperature is above 1600 F. and below 2075 F., cooling it sage therethrough accessible to the heat,

maintaining the rail at a uniform heat for a determinate period of time, and then coollng. 1

4. The method of heat-treating rails, which consists in taking a highly heated rail as it comes from the last forming operation, cooling it quickly to below 1000 F. to prevent the formation of laminated pearlite, conveying the rail to a heating furnace and heating it therein uniformly to be tween 1400 to 1500 F. to prevent the separation of free ferrite and for hardening, and then passing the rail through an annealing furnace in which the rail is heated uniformly to between 1000 F. and 1200 F. to soften, toughen and relieve it of strains. and then cooling.

5. The method of heat treating rails, which consists in taking a highly heated rail as it comes from the final forming operation, cooling it quickly in an air blast to below 1000 1+1, conveying it to a heating furnace and heating it therein until it reaches a uniform temperature above 14:00 R, then cooling rapidly in an oil bath and then passing it through an annealing furnace, in which the rail is uniformly heated to between 1000 F. and 1200 F., and finally cooling. q

6. The method of producing a hard and tough steel rail, which consists in taking a highly heated rail as it comes from the final forming operation, and cooling the surface of the rail quickly by means of an elastic fluid to a temperature below 1000 F. to prevent the formation of grain growths, then passing the rail through a heating furnace and heating the rail therein in all of its parts to a temperature above 1400 F. to get the rail in proper condition for hardening, cooling, and then annealing at a temperature below 1200 F. and above 1000 F.

ROY A. LEWIS.

W. ROBERT SHIMER. WILLIAM J. THOMAS. 

